Old English sweord, from Proto-Germanic *swerdan (cf. Old Saxon, Old Frisian swerd, Old Norse sverð, Swedish svärd, Middle Dutch swaert, Dutch zwaard, Old High German swert, German Schwert), related to Old High German sweran "to hurt," from *swertha-, literally "the cutting weapon," from PIE root *swer- (3) "to cut, pierce." Contrast with plowshare is from the Old Testament (e.g. Isaiah ii:4, Micah iv:3). Phrase put (originally do) to the sword "kill, slaughter" is recorded from mid-14c.